Manufacture of detergents and wetting agents from olefins



Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE MANUFACTURE OF DETERGENTS AND WET'IING AGENTS FROM OLEFIN S No Drawing.

This invention relates to the production of salts of secondary alkyl acid esters of polybasic inorganic acids having wetting, detergent and emulsifying properties by reacting olefins of 7 to about 24 carbon atoms per molecule with a polybasic inorganic acid to produce monoalkyl acid esters, and neutralizing the esters so obtained to convert them to the corresponding ester salts. The invention deals with an improved method of carrying out this process whereby the yield and quality of the ester salts obtained are substantially improved.

Secondary alkyl ester salts, particularly secondary alkyl sulfate sodium salts, are manufactured on a large commercial scale, and an immense amount of effort has been expended by a great many skilled chemists and engineers to make the process as efficient as possible. However, under the best methods of operation so far developed, a substantial amount of the starting olefin-containing hydrocarbons is not converted to the desired ester salts but appears instead as an oil-soluble extract or non-aqueous layer which is recovered from the aqueous phase containing inorganic matter and the bulk of the ester salts after the neutralization step of the process. This non-aqueous layer of unsulfated organic matter is usually referred to in the art as ester salts polymers, although it comprises; in addition to genuine polymers, varying proportions of unsuilfated olefins, secondary alcohols produced, for instance, by hydrolysis of polyalkyl esters and non-reactive hydrocarbons. This ester salts polymer, in many cases, represents more than 50% of the olefin input and constitutes a serious economicjloss in .estersalts manufacture, particularly since the usual method of disposing of this material has been to useit as fuel.

As previously pointed out, it has not been found feasible in practice to avoid the formation of substantial amounts of ester salts polymers which contain appreciable proportions of unsulfated olefins, even when using the most efiicient continuous sulfation methods; this, despite the ease and rapidity with which olefins as a class are sulfated. These facts have led workers in the art to the conviction that the olefins which have escaped conversion to sulfuric acid esters in the sulfation step of the process are, at least in part, exceptions to the general rule of easy and rapid conversion either because of isomerization or some other altera tion during the treatment or because of the presence in the starting olefinic mixture of some type of olefin which is particularly resistant to esterification. Under this explanation of the Application July 18, 1949, Serial No. 105,438. In Great Britain July 22, 1948 9 Claims. (Cl. 260-460) situation, even assuming that the olefins could be readily recovered from the other components of..the. estersalts polymers, it would appear unlikely that these olefins could be used efiectively for conversion to ester salts on a commercial scale.

iureacted olefins from all other constituents of ;ment utilizes the most advantageous sulfation procedure, namely, a very short time of contact with strong sulfuric acid.

According to the invention, the aforesaid ester salts polymers, after separation from the aqueous phase, if desired with the aid :of a solvent, are subjected to fractional distillation to produce a fraction containing the bulk of theolefins and secondary alcohols, the said fraction is subjected to a dehydration treatment with a dehydrating agent or catalyst so as to convert the secondary alcohols into -olefins,.and the olefins thus obtained are converted into secondary alkyl esters of inorganic polybasicacids.

Contrary to expectation, we have found that ,the-olefins recovered in this way from the ester saltspolymers not only form a satisfactory feedstock for the sulfation treatment, but thatester salts produced from such olefins are in many cases superior to those produced from the original unreacted olefins. The utilization of the olefin and secondary alcohol content of the ester salts polymers, which have hitherto generally been used as furnace fuel, effects an important reduction in the cost of the ester salts manufacture.

The olefins used as starting material ,in the production of the ester salts .are those which yield products valuable as wetting, detergent and/or emulsifying agents, preferably those having more than six carbon atoms. A suitable mixture of such olefins may advantageously be derived from petroleum, for example, by cracking a petroleum wax or .petrolatum. Mixtures of olefins, or even individualolefins derived from other sources, may, however, be .used, and .the expression olefins? as used herein is tobe understood as including individual olefins, in which case the expressions .secondary alk-yl sulfates,

be read in the singular.

In practice the vsegregration of the un- The process and apparatus for the sulfation and neutrahzation of the olefins may advantageously be those described and claimed in copending application of Buis entitled Method and Apparatus I01 Rapidly Mixing and Controlling the Temperature of Immiscible Liquids, Serial No. 72,558, filed January 25, 1949. Other suitable methods which may be used are described, for instance, in United States Patents 2,139,393, 2,152,292, 2,172,228 and 2,176,005.

In carrying the present invention into effect, the reaction mixture containing the neutralized aqueous phase and the ester salts polymers is first separated, preferably with the aid of a solvent, into an aqueous solution of the ester salts and inorganic matter, and a solution of the ester salts polymers in the extracting solvent, which may, for example, be a mixture of a petroleum spirit boiling at 90 C.- 110 C. and isopropyl alcohol or industrial methylated spirit. The polymers solution is subjected to fractional distillation to recover the solvent and a middle fraction containing the bulk of the olefins and secondary alcohols, and also of the unreactive hydrocarbons. The fractionation conditions required to achieve this depend largely on the nature of the olelins under treatment. In the case of olefins and secondary alcohols having 8 to 18 carbon atoms, we have found that they are contained in the fractions boihng below about 330 C. at atmospheric pressure. As a general rule, an advantageous cut point in distillation is the boiling point of the alcohol corresponding to the highest boiling olefin in the original feedstock.

The fractions obtained by this distillation operation, containing the bulk of the olefins and secondary alcohols, may amount to as much as 60% to 70% of the ester salts polymers and are dehydrated to convert the secondary alcohols into olefins. The dehydration may be carrieo. out in the liquid phase, for example, by boiling unoer reflux in the presence of a dehyoration catalyst such as zinc chloride or paratoluene sulfonic acid. We have found, however, that better results are obtained by conducting the dehydration treatment in the vapor phase, using, for example, phosphoric acid or alumina, etc. in a suitable form as catalyst. An activated alumina, preferably one high in bohmite, is the most desirable form of alumina for use as the catalyst. Suitable aluminas having preferably a relatively high surface area may be prepared from natural bauxite or may be synthetically produced. Whatever the source or nature of the alumina chosen, it is advantageous to employ one which has developed, or will develop during preparation and/or use of the catalyst, a large number of pores '10- -20 A., since such small pores appear to promote dehydration of alcohols. The preparation of adsorptive aluminas of controlled characteristics is a well established art, and suitable aluminas are commercially available so their method of manufacture need not be described. Substantially complete dehydration can readily be obtained. The temperature of such vapor phase dehydration is preferably above 250 0., most preferably between about 275 C. and 375 C., advantageously about 300 C. to about 325 C. A subatmospheric pressure is generally preferred, pressures ofthe order of about 1 mm. to 100 mm. ofmercury being suitable, although atmospheric pressure can be used with a slight decrease in bromine value of the product. Liquid hourly space velocities of the order of about to about 10 parts by weight of polymer tops per part of catalyst per hour are generally suitable with activated alumina catalysts. In vapor phase dehydration it isadvantageous to preheat the catalyst, as well as the vapor undergoing dehydration, in order to minimize fouling of the catalyst by condensation of liquid followed by carbonization thereon. This latter objective may conveniently be realized by injecting steam with the vapors undergoing dehydration, thereby reducing the dew point of the said vapors without adverse elfect on the dehydration operation. Usually about 10% to 20% by weight of steam based on the Weight of feed is satisfactory.

The dehydrated product consists mainly of olefins together with some unreactive hydrocarbons and this product can be recycled and sulfated in the normal way. It is found, however, that somewhat more drastic sulfation conditions (a greater percentage of sulfuric acid of greater strength, and a longer contact time) are desirable than for the sulfation of the original starting material. It may, for example, be desirable to use acid of 95% to 100% strength and acid to olefin molar ratios greater than 0.721, preferably between 1:1 and 1.5:1.

The olefins recovered by this dehydration treatment may thus be recycled for separate sulfation or they may be added to the olerins used as starting material for the suifation reaction. In I the latter event a slight increase in the severity of the sulfating conditions may be desirable to take account of the modifications of feedstock which has been effected by this recovery and recycling of unconverted olefins.

The following examples illustrate the invention: I

Example I A mixture of olefins obtained by cracking petroleum wax and having about 8 to 18 carbon atoms in the molecule is sulfated and neutralized as described in copending application Serial No. 72,558 previously referred to, hydrolysis of the dialkyl sulfates also being effected. The nonaqueous phase of the product is extracted with a solvent consisting of a mixture of a petroleum spirit boiling at 90 C. to 110 C. and isopropyl alcohol or industrial methylated spirit, and the resulting solution of ester salts polymers so obtained is subjected to fractional distillation at a pressure of 2 mm. of mercury. The solvent, and the fraction of ester salts polymers boiling below 330 C. at atmospheric pressure, are separately recovered. The polymers fraction is vaporized and passed, together with about 1; of its weight of steam, through a preheater raising the temperature to 300 C., and then through a column I of bauxite or gamma-alumina surrounded by a heating jacket,,the temperatures of the vapor, the steam and the jacket being'such as to keep the temperature of the alumina at.300 C. The resulting mixture of olefins and unreactive hydrocarbons is sulfated either by the short-contact method nsingsulfuric acid of 99.4% strength in a proportion of 1.5 mols of acid to 1 mol of olefins, or by stirring at a temperature maintained at 10 C.15 C. for 20 minutes using sulfuric acid of strength in a proportion of 0.85 mols of acid to 1 mol of olefins.

Alternatively, the mixture of olefins and unreactive hydrocarbons resulting from the dehydration treatment is added to the feedstock of unreacted olefins, the whole being sulfated under conditions slightly more drastic than those used .Emample II Olefins "38.2% by weight Alcohols 24.9% by weight Paraffins "36.9% by weight (by difference) The polymer tops were divided into two portions, one of which was dehydrated by passage 2 over 4-5 mesh alumina activated by heating at 400 C. for 2 hours before use. At a pressure of 1 mm. of mercury, a liquid hourly space velocity and acid added gradually at such arate that the temperature remained within the desired range (10 C.-l5 C.) bath was adjusted so that during continued stirring for the required time the temperature of the sulfation mixture was kept within the same range as during the acid addition. The product was then neutralized.

For short time sulfation conditions, the chief difference was that acid was added as quickly as possible, and no temperature range was specified. Maximum temperatures were usually between 35 C. and 40 C. Normally, the cooling bath was retained until the temperature had fallen to 20 C., when the product was neutralized. In all cases the sulfation mixture was neutralized with 20% (5 N) sodium hydroxide added in an amount equivalent to the acid used- The neutralization was carried out rapidly without excessive tem- .perature rise, and the neutralized mixture was Sulfation Conditions Yield of F d P 1 1Paster Stags ee o ymer ercen y Run Tops M018 Acid/ 3283 8 Sulfation 2 g f Weight of M01 Olefin+ Weight 1 Method of A Polymer Alcohol Percent Contact tion (mini) Tops l. 5 99. 4 none 41. 4 1. 75 99. 4 none 46. 6 l. 5 1 105. 2 none 43. 7 1. 5 1 105. 2 40 51. 0 d0 1. 5 105.2 20 45.6 Dehydrated. 0. 7 05. 0 20 32. 0 d0 1. 1 95. 0 20 40. l 1. 5 95. 0 none 43. 2 1. 5 95. 0 20 52. 5 l. 5 95. 0 G0 52. 7 0. 7 99.4 20 42. 1 l. 1 99. 4 20 54. 3 l. 1 99. 4 60 52. 5 1. 5 99. 4 none 51. 8 1. 5 99. 4 20 56, 1 l. 5 99. 4 60 53. 2

l 20% oleum.

of 7.5 and a temperature of 300 C. using by weight of steam based on the ester salts polymer tops, complete dehydration was obtained, the product having a bromine 'number of 49 to 50 (theoretical 48-51), corresponding to 58% olefinsas C14. l

A series of. runs were made-to determine .the optimum conditions of sulfation for conversion of the dehydrated and undehydrated ester salts polymer tops to ester salts. Both long and short contact time methods of sulfation were used. When applying long contact time sulfation conditions, the polymer tops were cooled, with stirrer running, by means of an ice bath, to below 5 C.,

These results show that the highest yields are obtained with dehydrated ester salts polymers and that under comparable sulfation conditions (compare runs 3 and 23) theincrease in yield obtained bydehydrating is quite substantial.

Example III Sulfatlon Conditions Yield of Percent Egg Sodium Run Feed M015 H9804 Time of Perce t B Sulfate in No. Polymer Tops I Concen- Stirring y 21% Ester fig f g am tiger lcid 9 aggy Salt Soln eig di ion of Product Alcohol Percent (mm) Tops 1. 2 95. 0 20 10-15 27. 9 21. 8 0. 85. 99. 4 20 -20 19. 6 21. 8 1. 0 99. 4 15-20 28. 7 15. 8 1. 2 99. 4 15-20 29. 5 20. 1 0. 95. 0 20 10-15 23. 7 18. 8 l. 5 i 95.0 20 l0-15 33. 4 24. 3 0. 85 99. 4 20 10-15 34. 3 9. 2 1. 0 99. 4 20 15-20 36. 3 11.2 1. 5 99:4 20 15-20 36. 9 21. 1

After acid addition, the cooling These results show not only that the best yields are obtained by dehydrating the polymer tops, but also that desirably low medium sulfate to ester salts ratios can only be obtained from the dehydrated polymer tops.

Tests of the products of the invention by the Draves test showed that they have markedly superior wetting power compared with the ester salts initially produced in the process. Thus, the wetting power of the ester salt from the dehydrated Clo-C18 polymer tops of Example II averaged 240, and those from the C8-C18 polymer tops of Example III averaged 190, compared with 100 for the ester salts initially obtained. The performance of these ester salts was also superior in redeposition tests to ester salts produced in the process from which the ester salts polymers were derived.

The material overall improvement in ester salts yield obtainable by the process of the invention is illustrated by the following results for ester salts from 08-018 cracked distillate, where the initial ester salts yield was '70 by weight of the cracked distillate and the ester salts polymers 56.5%. Taking off 65% of the ester salts polymer as tops, which yield 35% by weight of ester salts, give a 12.6% yield of ester salts on the original cracked distillate, or a final yield of 82.6% which represents an increase of almost 20% over the usual process.

It will thus be seen that the process of the invention offers many advantages, particularly with respect to yield and quality of ester salts produced, compared with conventional methods of producing alkyl sulfate salts. While sodium alkyl sulfate production has been emphasized in order to simplify the description, it will be apparent that the invention is not limited thereto but that, by substitution of phosphoric acid, boric acid or other polybasic inorganic acids for sulfuric acid in the process, other alkyl acid esters may be obtained in the same way and that these may be converted not only to sodium salts but that other alkali metal or alkaline earth metal or heavy metal or ammonium or amine salts'may be similarly produced by the use of other suitable bases in the process. Still other variations in the process may be made without departing from the invention which is not limited by any theory proposed in explanation of the improved results which are obtained.

We claim as our invention:

1. In a process of producing ester salts by reacting olefln-containing hydrocarbon with a polybasic inorganic acid and neutralizing the acid esters produced whereby a mixture of unreacted olefin-containing hydrocarbon, secondary alcohol corresponding to said olefin and olefin polymers is obtained, the improvement which comprises contactinga substantially polymer-free portion of said mixture comprising an olefin and a secondary alcohol with a dehydration catalyst under dehydration conditions to convert said secondary alcohol to the corresponding olefin, reacting the olefinic product with a polybasic inorganic acid, and neutralizing the acid ester thus produced whereby the yield of ester salts is increased.

atoms per molecule with sulfuric acid and neutralizing the resulting alkyl acid sulfate, wherein a mixture of unsulfated olefin, a secondary alcohol corresponding thereto and an olefin polymer is obtained as a by-product, the improvement which comprises fractionating said mixture to separate therefrom a fraction comprising said unsulfated olefin and said secondary alcohol substantially free from said polymer, contacting the thus separated fraction with a dehydration catalyst under dehydration conditions to convert the said secondary alcohol to an olefin having the same number of carbon atoms per molecule), lsulfating the olefinic product, and neutralizing the acid alkyl sulfate thus produced whereby the yield of secondary alkyl sulfate salt in the process is increased.

4. A process in accordance with claim 3 wherein the dehydration of said secondary alcohol is carried out in the presence of an activated alumina catalyst at a temperature of 275 C. to 375 C.

5. A process in accordance with claims 3 or 4 wherein the sulfation of the olefinic product of the dehydration step is carried out by reaction with sulfuric acid of 95% to about 105% concentration using about 1:1 to about 1.521 moles of acid per mole of olefin, a temperature of 0 C. to 20 C. and a contact time of about 1 to 20 minutes.

6. A process of producing sodium alkyl sulfate salts of 8 to 18 carbon atoms per molecule which comprises reacting a C8 to C18 fraction of olefins and parafiins from the cracking of parafiin wax with sulfuric acid of 90% to 100% concentration, using 0.621 to 12:1 moles of acid per mole of olefin, at 10 C. to 25 C. and a contact time of about 1 to 20 minutes, reacting the resulting alkyl sulfates with sodium hydroxide to produce sodium alkyl sulfate salts, separating the product into an aqueous phase comprising the bulk of the sodium alkyl sulfate salts and a phase comprising unreacted olefins and'secondary alcohols of 8 to 18 carbon atoms,

2. A process in accordance with claim 1 whereparaflilns and olefin polymers, distilling said olefin-containing phase to separate therefrom a' fraction comprising said olefins and secondary alcohols of 8 to 18 carbon atoms from higher boiling components of the mixture, contacting the thus separated fraction with a dehydration catalyst under dehydration conditions to con.

vert the said secondary alcohols to olefins having the same number of carbon atoms per molecule, reacting the dehydration product with sulfuric acid under more drastic conditions than are used in the first said sulfation, and neutralizing the acid alkyl sulfates thus produced with sodium hydroxide whereby the yield of sodium alkyl sulfate salts is increased.

7. A process in accordance with claim 6 wherein the dehydration is carried out under subatmospheric pressure in the presence of an activated alumina catalyst with about 10% to 20% 1 alcohol to an olefin having the same number of UNITED STATES PATENTS carbon atoms per molecule, reacting the olefinic Number Name Date product with a polybasic inorganic acid, and 1345665 Isham Feb. 16 1932 neutralizing the acid ester thus produced wherel9984l1 Marley Apr. 1935 by the yield Of ester salts is increased. 5 Fulton t 1 9. A process in accordance with claim 8 where- 2214051 Gaylor Sept 1940 in the dehydration of said secondary alcohol is u carried out in the presence of a dehydration FOREIGN PATENTS catalyst at a temperature between 250 C. and Number Country t 10 424,951 Great Britain May 29, 1933 PHILIP J GARNER 459,117 Great Britain Dec. 28, 1936 HENRY SHORT' OTHER REFERENCES REFERENCES CITED Henne et al.: J. Am. Chem. Soc, vol. 66,

The following references areof record in the 5 pages 4 (1944) file of this patent: 

1. IN A PROCESS OF PRODUCING ESTER SALTS BY REACTING OLEFIN-CONTAINING HYDROCARBON WITH A POLYBASIC INORGANIC ACID AND NEUTRALIZING THE ACID ESTERS PRODUCED WHEREBY A MIXTURE OF UNREACTED OLEFIN-CONTAINING HYDROCARBON, SECONDARY ALCOHOL CORRESPONDING TO SAID OLEFIN AND OLEFIN POLYMERS IS OBTAINED, THE IMPROVEMENT WHICH COMPRISES CONTACTING A SUBSTANTIALLY POLYMER-FREE PORTION OF SAID MIXTURE COMPRISING AN OLEFIN AND A SECONDARY ALCOHOL WITH A DEHYDRATION CATALYST UNDER DEHYDRATION CONDITIONS TO CONVERT SAID SECONDARY ALCOHOL TO THE CORRESPONDING OLEFIN, REACTING THE OLEFINIC PRODUCT WITH A POLYBASIC INORGANIC ACID, AND NEUTRALIZING THE ACID ESTER THUS PRODUCED WHEREBY THE YIELD OF ESTER SALTS IS INCREASED. 